The present invention relates to fastening devices in an air conditioner. More specifically, the present invention relates to apparatus for joining a flangeless end plate of a heat transfer coil in an air conditioner to the base pan thereof.
In air conditioning units and particularly self contained air conditioning units such as a window or through-the-wall units, the air conditioner is divided into an evaporator section and a condenser section by a partition. An evaporator consisting of a finned tube heat exchanger is mounted to the base pan of the unit in the evaporator section and a condenser also consisting of a finned tube heat exchanger is mounted in the evaporator section to the base pan.
Previously, finned tube heat exchangers, such as the evaporator or condenser in an air conditioner, were constructed with copper tubes; however, with the advent of new technology, it has been possible to construct heat exchangers with aluminum tubes. The heat exchangers are assembled by inserting a plurality of tubes through openings in pre-stamped fins. End plates are then attached to hold the heat exchanger together. The final assembly step is to bond semicircular shaped return tubes to the open ends of the tubes mounted in the heat exchanger thereby providing for circular flow thru the heat exchanger.
A method being used to connect the semicircular shaped aluminum tubes to the tubes in the heat exchanger is to bond the tubes together by an ultrasonic dip process in which the end of the heat exchanger containing the joints to be bonded is dipped into an ultrasonically excited molten bath containing a zinc-aluminum alloy.
Prior to the ultrasonic dip process, the end plates had flanges at right angles to the face of the end plate. The flanges were then simply connected directly to the base pan to mount the heat exchanger. However, the end plate flanges extended beyond the end plate as did the semicircular shaped tubes. Therefore in the ultrasonic dip process the flanges interfered with the bonding of the semicircular tubes with the straight tubes and it bacame necessary, as well as less expensive, to fasten the end plate to the base pan without the use of flanges.